I thought that I replied to this yesterday but I can't see it here so I'll post again...
There's a potential problem here. Consider what voltage you will be getting from the MCU pin. It will _not_ be 0V, 5V, or Hi-Z. Most 5V devices aim for TTL compatibility. From memory that allows a low to be up to 0.8V and a high to be as low as 2.0V. Therefore it is possible for your 'high' voltage to be below the 2.5V centre voltage.
This is of course the worst case scenario, but the LED barrier voltage is also conspiring against you. This varies from device to device but is typically around 1.7V. 2.5 + 1.7 = 4.2V needed from the pin in its high state, which is asking a lot from a 5V device, particularly when you are drawing current from it.
Do yourself a favour. Put an H-bridge in there.